Posted
by
timothy
on Wednesday June 09, 2004 @04:51AM
from the those-things-wake-up-hungry dept.

yokem_55 writes "According to this article on Yahoo News, Mars rover engineers are beginning to consider the possibility that the rovers may be able to survive the oncoming Martian winter in a hibernation mode, and then return to activity when spring returns to the red planet. The article ends with a quote from Steve Squires speculating that, 'we're looking at the final demise of these vehicles perhaps as late as the onset of our second winter on Mars.'"

1) during winter sun is weaker, would get less power
2) I'm sure some things, like the batteries, are affected by the temperature. In general lower temperatures increase activation energy barriers, so there's a chance the batteries will be weaker as well
4) Temperature gradient between relatively hot parts of operating rover (such as computer equipment, etc) and outside air will stress the rovers; also temperature cycling from turning off at night and turning back on in daytime will take the rover's equipment along a fairly large range of temperatures which is a good way to break delicate equipment.
3) I sure don't want to be chipping at rocks when it's -100C.... But then again the rovers probably don't care about frostbite as much

As one who actually works on the mars program (orbiters, though, not the rovers), I can tell you that MANY different options were considered. Most weighed enough that you'd have to sacrifice instrumentation to implement them, however, and as the nominal mission was only nintey days, it was decided that more guaranteed science results during that period were preferable to uncertian return during the extended mission.

The best idea I've heard so far for dust removal was to use electrostatic forces to make it all jump off, but for similar reasons this was not flown either.

Yes. Yes. Yes...
Bureaucratic cowards! There are so many projects that have been snuffed because NASA feared negative PR in the event of failure. NASA is the Cathedral! However, the general population does view space travel as a bit of a frivolous thing and so its easy to sympathize with their plight.
Here is one project that NASA killed that actually offered the possibility of interplanetary travel. Project Orion [angelfire.com] (projectorion.com doesn't seem to be around anymore.)

Not exactly. First of all, there are the political issues--NO ONE wants to launch a nuclear reactor into space in case the rocket blows up, as an explosion could set off a nuclear explosion too. Second of all, there are really two types of nuclear reactor. There is the kind we use on earth, which requires massive cooling (yes, not even the cold of mars would be enough). The second type is a radioactive reactor, which simply uses the radiation from a chunk of highly radioactive material for power. Many of the space probes, such as Voyager, used this type of reactor.

KIRK: Your timing is excellent, Mr.Scott. You've fixed the barn door after the horse has come home. How much refit time till we can take her out again?

SCOTTY: Eight weeks, sir.(as Kirk opens his mouth) But you don't have eight weeks so I'll do it for ya in two.

KIRK: (considers) Mr. Scott. Have you always multiplied your repair estimates by a factor of four?

SCOTTY: Certainly, sir. How else can I keep my reputation as a miracle worker?

KIRK: Your reputation is secure, Scotty.

Hey, I've used this as a rule of thumb for computer work time estimates, and while a factor of four is usually excessive (unless dealing with a real asshole), two is always a good idea, and three is good if you're a bit unsure of the situation. If you've worked in computers you know how unpredictable a troubleshooting situation can be. I can only imagine how much more complex it is in the engineering world.

NASA does astronomy. To be very blunt and honest, astronomy provides very few concrete short-term benefits.

Really? Astronomy? Well, they do some of that, but every look at NASA Langley. [nasa.gov] They do aerospace research, have aided Boeing in desinging almost every aircraft they built. Langley has produced some of the finest Structures and Materials research. And has many unique test facilities and wind tunnels that nobody else has.
Or what about NASA Glenn? [nasa.gov] They do space research, but their studies into new and unique propulsion systems dont look like astronomy to me.

NASA is a low-frills research organization. They get poor public support, and even more limited congresional support, yet they produce some amazing stuff. The problem that I see is, the public thinks exactly like your first sentance, they dont view NASA as an incubator for new expensive tech that can mature and develop well only in a gov funded (ie no worries about profit) situations. If you dont belive me on that point, go look at the papers on Optics, Radar, Ultrasonics, look at aircraft structures, etc, somewhere in there is a NASA engineer who developed, or help develop core features that are curtial today.

This is why NASA spends so much effort marketing what they have done -- for instance, providing free, beautiful pictures that consist entirely of false-color images that have been tweaked by hand to look attractive...they're more a credit to the artistic nature of the postprocessors than to the people doing the research itself.

I think that is very insulting. Do you really believe that it is more of a feat to
adjust some color scales than it is to
send a spacecraft to another planet at distances of 300 million miles or more, have it operate without any repairs for years at a atime, survive the heat & cold of space, the forces of re-entry, launch etc etc.? The images are generally false-color composites, true. But they are not "retouched". The difference is between one of choosing how to remap wavelengths your eye can't see into colors it can see, and flat-out changing images. JPL does the former, and not the latter.

So all NASA has to do is make significant public underestimates of their mission potentials. That way, after completing, say, 10% of their expected work, they can announce that the mission "is a success".

That's not how things are done. I don't think you even begin to grasp how challenging some of this stuff is - the rover team was ecstatic when both rovers worked (the bets in my group were for at least one loss). Then there is the issue with dust accumulation on the solar panels, and thermal cycling. Nobody I know thought that the rovers would last this long, and it remains to be seen if they will make it to winter.

You have to rememeber that many of these missions are selected after competitions among various university and industry groups. This means that you have to sell a mission to the review boards; you can't do that if you under-promise. If you only claimed you could do 10% of what you think you could actually do, then some other group is going to propose a mission to do 20% of what is possible - and they will look much better on paper and so get chosen. And these proposals are not secret, so NASA can't turn around and tell the public that mission will do less than it proposed for.

The result is NASA tends to define success criteria close to what is reasonably expected based on some pretty detailed mission analysis work.

Another point to remember is that the mission probability of success is like a chain - no stronger than the weakest link. Which means that there are almost always a few events that have all the risk (launch, landing); once past those there isn't much that can kill a spacecraft, at least not until old age starts to set in. And one thing about JPL - their stuff is built to last. That's why the mission achievements are bimodal - either failure, or way longer life (and greater success) than expected.

They could have sent a nuclear power source up there just as they did early on. But they lost their balls and figured it was politically safer to go with a crappy solar solution rather with a long term nuclear solution

I'd be surprised if they would have picked up much flack on launching a couple of small RTG's on those. They would have been so small that they wouldn't have been a problem even if they did crash on launch.

More pratically, I'm guessing the weight limitations were more of a concern. RTG's (the simplest and most common form of nuclear power for spacecraft) are heavy and inefficent. Only a very small portion of the heat generated is converted to power (they usually use a thermocouple device, which is very inefficent). Solar panels are much lighter and at the orbital distance of Mars, probably produce more power than an RTG, pound for pound. Out at Uranus its a different story, solar panels are nearly worthless out there.

Perhaps they could have used an extra-small RTG as a heater though, perhaps built into structural members to save the weight of the casing.

But now, JPL is happy if they get a few extra months over their initial 3 month plan.

Do you even really know why all NASA missions are so short, and then they always have an "extended mission"? Do you really think it's because NASA's aspirations are so low?

The reason is simple. The cost of the hardware itself is cheap. The cost of the people analyzing data is far more expensive. NASA's missions are so short because when the mission planners present the budget for grant review, in order to keep the cost sane, they plan a very short mission, and then hope to get funding for the extended mission.

A billion bucks for 3 months of science...only Dr. Pangloss could be happy with that.

This is the cost of science nowadays, and it's not hardware - it's people. If you want longer missions, fund NASA better.

Instead of creeping inch by inch, the Rovers could have moved foot by foot or gasp - yard by yard!

If you run across terrain that you don't know, you'll trip. Likewise, if the rovers move quickly over terrain they don't know, they could flip. There's no way to build enough fault tolerance in them to manage every scenario. Instead, they just move slowly.

Perhaps they could have even found the remains of Beagle and figured out what went wrong with it.

This better have been a joke. Mars is a planet. It has as much land area as Earth does (yes, that's true, as Mars has no oceans). The only thing that could've found Beagle would've been a human expedition with a very long range vehicle. A robotic rover attempting to travel that far would've been orders of magnitude more expensive, and it probably would've failed along the way.

Actually, it looks like Opportunity is just south of the equator as well. So they're both in the southern hemisphere. Spirit is at latitude 14.735 degrees south and longitude 175.39 degrees east, while Opportunity is at latitude 1.95 degrees south and longitude 5.53 degrees west.

Um, to paraphrase Inigo Montoya, I read your link and I don't think it means what you think it means. The report is on the insurance of private payloads, not government ones. In general, the government doesn't take out insurance. If they did, then there would be no problem in coming up with the funding to replace Columbia as the policy would pay for the conversion of the Enterprise frame to a launch-capable vehicle. Instead, they have to ask Congress for the funds.

If NASA didn't insure the Shuttles, that's pretty convincing evidence that they wouldn't have insured the piddling unmanned Mars Rovers. Also, it is an elementary logical fallacy to ask someone to prove a negative. You did know that, didn't you?